don't get into a bidding war on e-bay. you only drive up prices unnecessarily.
log in 2 minutes before end-of-bid. Decide on your top price - you won't have time to react and change, so pick what works for you.
Now, last 15-20 seconds, enter your bid. No one else will have time to react - If they've got a higher bid, you lost it, if not, it's yours.